This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Over the period of the past three decades, the number of overweight/obese individuals (children, adolescents and adults) has reached epidemic proportions in the United States. Several factors are recognized to play a role in the etiology of the obesity epidemic. Altered nutritional experiences during early periods of life are recognized to impact on the development of metabolic systems (metabolic programming effects) resulting in predisposition to adult-onset metabolic diseases. The purpose of this study is to investigate the effects of early postnatal nutritional manipulation on the development of the hypothalamic melanocortin system in the rat. These studies use a rat model developed by Dr. Patel whereby rat pups are either raised on a high fat (HF) diet (similar to maternal milk) or a high carbohydrate (HC) diet. Offspring raised on a HC diet are hyperphagic and obese as adults. These studies will use a variety of neuroanatomical techniques to investigate the immediate and long-term impact on the hypothalamic melanocortin system.